Influence and experiment of cable-net manufacturing errors on surface accuracy of mesh reflector antennas

Cable-net structures are of substantial importance in the construction of large mesh reflector antennas.Owing to the inevitable errors in their manufacturing process,the reflector surface accuracy deteriorates.This study makes a comprehensive investigation of random manufacturing errors during constructing the mesh reflector antennas,and analyze its influence on reflector surface accuracy.Firstly,the sensitivity of reflector surface accuracy with respect to the random errors of the unstressed cable length is mathematically deducted.Secondly,a non-button connecting method is proposed and analyzed to reduce manufacturing errors.Thirdly,two physical experiment models based on 2.62-meter mesh reflector antenna are made.Finally,numerical examples and experimental tests are given to demonstrate the effectiveness of the proposed method.Compared with the traditional method,the proposed method can effectively reduce the influence of the manufacturing errors on the reflector surface accuracy.Moreover,the reduction in the sizes of the nodes also reduces the risk of entanglement of the mesh reflector antenna during the deployment process,and thereby improves the deployment reliability.

Clinically relevant factors associated with quantitative optical coherence tomography angiography metrics in deep capillary plexus in patients with diabetes

Background:To test clinically relevant factors associated with quantitative artifact-free deep capillary plexus(DCP)metrics in patients with diabetes mellitus(DM).Methods:563 eligible eyes(221 with no diabetic retinopathy[DR],135 with mild DR,130 with moderate DR,and 77 with severe DR)from 334 subjects underwent optical coherence tomography-angiography(OCT-A)with a swept-source OCT(Triton DRI-OCT,Topcon,Inc.,Tokyo,Japan).Strict criteria were applied to exclude from analysis those DCP images with artifacts and of poor quality,including projection artifacts,motion artifacts,blurriness,signal loss,B-scan segmentation error,or low-quality score.A customized MATLAB program was then used to quantify DCP morphology from the artifact-free DCP images by calculating three metrics:foveal avascular zone(FAZ),vessel density(VD),and fractal dimension(FD).Results:166(29.5%)eyes were excluded after quality control,leaving in the analysis 397 eyes(170 with no DR,101 with mild DR,90 with moderate DR,36 with severe DR)from 250 subjects.In the multiple regression models,larger FAZ area was associated with more severe DR(β=0.687;p=0.037),shorter axial length(AL)(β=−0.171;p=0.003),thinner subfoveal choroid thickness(β=−0.122;p=0.031),and lower body mass index(BMI)(β=−0.090;p=0.047).Lower VD was associated with more severe DR(β=−0.842;p=0.001),shorter AL(β=0.107;p=0.039),and poorer visual acuity(VA)(β=−0.133;p=0.021).Lower FD was associated with more severe DR(β=−0.891;p<0.001)and with older age(β=−0.142;p=0.004).Conclusions:Quantitative artifact-free DCP metrics are associated with VA,DR severity,AL,subfoveal choroidal thickness,age,and BMI in diabetic patients.The effects of ocular and systemic factors should be considered for meaningful interpretations of DCP changes in DM patients.